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From Peter Kriens <Peter.Kri...@aQute.biz>
Subject Re[4]: Maven repository security
Date Wed, 02 Aug 2006 14:19:36 GMT
There are a number of verifications. Jarsigner verifies that the
hashes are ok and the signer file is correctly signed. This is the
technical integrity that matches traditional checksumming. There is no
API. You can easily check this by using a JarInputStream/JarFile and getting
each entry. If the file is signed, the the input stream will do all
the nasty work for you; it throws an exception when it runs into
differences.

This obviously only tells you that the hashes are ok and the file has
not been tampered with. As a policy, require that the manifest is
signed and all resources are listed in the manifest. This is not
mandatory but there are exploits if you don't.

Next is getting the certificate that was used to sign the jar (which
can contain a chain). This is trivial, do getCertificates on each Jar
Entry. Again, I would ensure that ALL entries return the same
certificates indicating ALL files are signed by All signers.

Take a look at http://java.sun.com/products/jce/doc/guide/HowToImplAProvider.html#MutualAuth

It is really not as hard as it sounds. The REAL hard part is the
Apache trust model.

Kind regards,

     Peter Kriens





Trust is based
SL> On 02/08/06, Peter Kriens <Peter.Kriens@aqute.biz> wrote:
>>
>> 2a. JAR file verification
>>    Verifying a JAR file is not that hard as it sounds. Jarsigner can
>>    do it, and it is not that hard to code up. However, why do you need to
>>    do this? The class loader will do this properly during class loading
>>    which gives you end-to-end security. Notice that a signed JAR does
>>    not tell you it is trustworthy, it just tells you who signed it.
>>    You need to decide how much you trust the signer (or the signer of
>>    the signer certificate if you use certificate chains).


SL> I dont think jarsigner does work. This is why ant doesnt have a
SL> <verifysigned> task; I backed it out once we became aware of all the
SL> deficiencies of the code. It looks like it works, but it doesnt check
SL> that a JAR is signed by anyone you trust, and it doesnt change its
SL> return code depending on whether the thing was validated or not. All
SL> you can do is look at the output string and hope it doesnt change from
SL> version to version.

SL> Maybe java1.4 or 1.5 has the API calls to validate the CA chain of the
SL> signatures.

SL> -steve
SL> -steve

-- 
Peter Kriens                              Tel +33467542167
9C, Avenue St. Drézéry                    AOL,Yahoo: pkriens
34160 Beaulieu, France                    ICQ 255570717
Skype pkriens                             Fax +1 8153772599


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